An optical system used in a charged particle beam inspection system. The optical system includes one or more optical lenses, and a compensation lens configured to compensate a drift of a focal length of a combination of the one or more optical lenses from a first medium to a second medium.

The present disclosure proposes an anti-rotation lens and using it as an anti-rotation condenser lens in a multi-beam apparatus with a pre-beamlet-forming mechanism. The anti-rotation condenser lens keeps rotation angles of beamlets unchanged when changing currents thereof, and thereby enabling the pre-beamlet-forming mechanism to cut off electrons not in use as much as possible. In this way, the multi-beam apparatus can observe a sample with high resolution and high throughput, and is competent as a yield management tool to inspect and/or review defects on wafers/masks in semiconductor manufacturing industry.

A system is disclosed. The system includes a stage assembly configured to receive a specimen and maintain a height of the specimen at a first working distance height during a first characterization mode and an additional working distance height during an additional characterization mode. The system further includes an illumination source configured to generate an illumination beam. The system further includes an illumination arm including a set of optical elements configured to direct a portion of the illumination beam including illumination of a first wavelength to the specimen during the first characterization mode, and direct a portion of the illumination beam including illumination of an additional wavelength to the specimen during the additional characterization mode. The system further includes a detector assembly configured to receive illumination emanated from the specimen, and a controller configured to determine a specimen height value based on the illumination received by the detector assembly.

According to one embodiment, a drawing method includes acquiring a first arrangement information indicating an arrangement state of a stepped portion on a substrate. The method further includes acquiring a height information indicating a height of the stepped portion. The method further includes measuring a height of the substrate. The method further includes calculating a focus map indicating a distribution of beam focus values of an electron beam according to a drawing location on the substrate on a basis of the acquired first arrangement information and the height information, and the measured height of the substrate. The method further includes drawing a pattern on the substrate by an electron beam with a beam focus value determined on a basis of the calculated focus map.

In one embodiment, a multi charged particle beam writing apparatus includes an objective lens adjusting focus positions of multiple beams, an astigmatism correction element correcting astigmatism of the multiple beams, an inspection aperture allowing one of the multiple beams to pass therethrough, a deflector deflecting the multiple beams and causing the multiple beams to scan over the inspection aperture, a current detector detecting beam currents of the individual multiple beams after passing through the inspection aperture, a beam image formation unit forming a beam image based on the detected beam currents, a feature amount calculation unit generating a first waveform and a second waveform by adding brightnesses of the beam image in a first direction and in a second direction, and calculating a first and a second feature amounts from the first and the second waveforms, and a parameter calculation unit calculating an exciting parameter that is to be set for the astigmatism correction element based on the first feature amount and the second feature amount.

An optical system used in a charged particle beam inspection system. The optical system includes one or more optical lenses, and a compensation lens configured to compensate a drift of a focal length of a combination of the one or more optical lenses from a first medium to a second medium.

Multi-beam e-beam columns and inspection systems that use such multi-beam e-beam columns are disclosed. A multi-beam e-beam column configured in accordance with the present disclosure may include an electron source and a multi-lens array configured to produce a plurality of beamlets utilizing electrons provided by the electron source. The multi-lens array may be further configured to shift a focus of at least one particular beamlet of the plurality of beamlets such that the focus of the at least one particular beamlet is different from a focus of at least one other beamlet of the plurality of beamlets.

Systems and methods to focus and align multiple electron beams are disclosed. A camera produces image data of light from electron beams that is projected at a fiber optics array with multiple targets. An image processing module determines an adjustment to a voltage applied to a relay lens, a field lens, or a multi-pole array based on the image data. The adjustment minimizes at least one of a displacement, a defocus, or an aberration of one of the electron beams. Using a control module, the voltage is applied to the relay lens, the field lens, or the multi-pole array.

Provided is a scanning electron microscope which can perform high-speed focus correction even when an electron beam having high energy is used. The scanning electron microscope includes an electron optical system including an electron source 100 that emits an electron beam and an objective lens 113, a sample stage 1025 which is disposed on a stage 115 and on which a sample 114 is placed, a backscattered electron detector 1023 which is disposed between the objective lens and the sample stage and is configured to detect backscattered electrons 1017 emitted due to interaction between the electron beam and the sample, a backscattered electron detection system control unit 138 which is provided corresponding to the backscattered electron detector and is configured to apply a voltage to the backscattered electron detector, and a device control calculation device 146. The objective lens has an opening in a stage direction, and the device control calculation device performs focus correction of the electron beam by controlling the voltage applied to the backscattered electron detector from the backscattered electron detection system control unit.

The present invention relates to a method for examining a beam of charged particles, including the following steps: producing persistent interactions of the beam with a sample at a plurality of positions of the sample relative to the beam and deriving at least one property of the beam by analyzing the spatial distribution of the persistent interactions at the plurality of positions.